Safety ground clamp



Oct. 7, 1952 o. w. s. FREAR 2,613,243,

SAFETY GROUND CLAMP Filed Nov. 5. 1948 Oscar W. 5. Frear Patented Oct. 7, 1952 UNITED STATES PATENT OFFICE Oscar W. S. Frear, Williamsport, Pa. Application November 5, 1948, Serial No. 58,473 I The present invention relates to certain new and useful improvements in a structurally and functionally novel safety ground clamp and the obvious objectof the invention is to provide for the grounding of highvoltage electrical equipment which has been de-energized and taken out of service for repair; equipment such as, for example, transformers, oil circuit breakers, high tension electrical lines, capacitators, generators, condensers and the like.

The outstanding purpose of the invention is for temporarily grounding the stated equipment whereby to safeguard and protect the lives of workmen working on ole-energized or dead equipment and is not to be confused with so-called live line connectors and clamps.

j Another object of the invention is to provide a safety; ground clamp characterized by a pair of opposedpivotally connected gripping jaws for an overhead line or other current conductor, said jaws being provided with selectively usable and reliable grippinggsurfaces to accommodate the variousgages of lines encountered ranging from small to large.

In reducing to practice a preferred embodiment of the invention I provide a pair of complemental jaw units hingedly connected together, one unit carrying a feed and adjusting screw and the other unit having a socket for accommodating the headed end of the screw with the walls of the socket having predetermined inclined planes in order to provide not only a swivel connection but a connection with requisite end thrust properties for swinging and effectively clamping the movable jaw against the relatively stationary jaw.

A further object of the invention is to provide 'a simple and feasible safety ground clamp which functions admirably well in taking a given line out of service for maintenance, such as changing of insulators or repairing the line in a manner to minimize injury to workmen, said clamp being highly simple, efficient in action and economical to all concerned.

Other objects and advantages will become more readily apparent from the following description and the accompanying illustrative drawings.

In the drawings, wherein like numerals are employed to designate like parts throughout the views:

Figure l is a perspective view of a safety ground clamp constructed in accordance with the principles of the present invention showing the jaws partly open;

Figure 2 is a central longitudinal sectional view on a slightly enlarged scale, with parts in eleva- 1 Claim. (Cl. 173-273) tion and showing the opening and closing movements of the movable jaw in full and dotted lines,

respectively;

Figure 3 is a cross-section on the line 3-3 of Figure 2, looking in the direction of the arrows; Figure 4 is a horizontal fragmentary section on the horizontal line 4-4 of Figure 2, looking in the direction of the arrows; I

Figure 5 is a bottom plan view of the movable jaw.

Referring now to the drawings by distinguishing reference numerals it will be observed that there are three principal parts, namely, the primary jaw unit I, the complemental secondary jaw unit 8 and the adjusting and clamping screw 9. a

The unit I comprises an elongated jaw ID with a milled gripping surface II. Jaw I6 is at one end of the body of said unit and at the opposite end I provide a lug I2 with an aperture I3 to accommodate the ground wire (not shown). At th junctnral point between thelug and jaw I provide a lateral extension which constitutes a mount l4 and this has a horizontal screwthreaded hole I5 to accommodate the threads It of the adjusting and retaining bolt ll, which latter, at the left hand end, may be provided with a tool lug I3 to facilitate turning the same. The

opposite end of the screw is formed with a substantially spherical head or ball Ila. Unit 1 also has an ear I9 which serves to accommodate a pair of spaced parallel complemental ears 2!] formed as an integral part of the jaw unit 8. The several ears are hinged or pivoted together as at 2| and the unit 8 is located opposite to the jaw Ill and includes a relatively movable companion jaw 22. The face of the jaw 22 has several distinct transverse grooves or notches, the larger one denoted at 23, the smaller one at 24 and the intermediate one at 25. The last two grooves are diagonal to the longitudinal dimension of the jaw unit and the first notch 23 is at approximate right angle. Said jaw unit is recessed to provide what maybe identified as a socket 26 for the head Ila and the walls of the socket are properly shaped to provide cams or inclined planes as brought out in Figure 2. Consequently, by threading, the feed screw I'I back and forth through the mount I4, the coaction of the ball jointing head Ila with the socket and inclined surfaces 26 provides not only the desired hinging movement of the relatively movable jaw but maintains the desired fixed clamping result. Incidentally, the slot or notch 23 will accommodate a heavy conductor and may be used for 2,613,243 v Y a grounding 350,000 CM to 750,000 CM wire. The intermediate notch 25 is for grounding /0 t 300,000 CM wire; While the remaining smaller slot 24 is for grounding No. 6 to 1/0 wire.

As stated, the clamp is not to be confused with similarly constructed and appearing live lines connectors and is primarily adapted for temporarily grounding different types of electrical apparatus while. providing protection for men working on de-energized or dead equipment, as will be clear to persons skilled in the art to which the invention relates.

It is thought that persons skilled in the art to which the invention relates will be able to obtain a clear understanding of the invention after considering the description in connection with the drawings. Therefore, a more. lengthy description is regarded as unnecessary.

Minor changes in the shape, size and arrangement of details coming within the field of invention claimed may be resorted to in actual practice, if desired.

Having described the invention, what. is claimed as new is:

A. high tension line, safety ground clamp for the protection of workmen working on deenergized or dead electrical equipment which has been temporarily taken out of: service for repair comprising a relatively stationary jaw unit embodying a one-piece elongated body of current conductingmaterial fashioned at one end into a relatively long substantially flat faced jaw, and fashioned at its other end into an apertured line attaching lug, said lug being in a substantial plane with said body and jaw, said jaw being provided intermediate its ends with a lateral ear,

and said body being provided adjacent said ear and inwardly of the apertured lug with a permanentlateral extension, the latter substantially paralleling and bein in alignment with said ear and having a, screw-threaded hole in approximate parallelism with said jaw and constituting a mount for a feed screw, a relatively movable jaw unit also of current conducting material and including a body portion having a jaw opposed to said first-named jaw and swingable toward and from the latter, said relatively movable jaw unit being of a length approximately equal to that of said first-named jaw and having an end portion terminating in close spaced parallelism with said mount and provided with a cavity forming a socket, said socket hooding over said ear and being open on the side facing and confronting said extension and open at the bottom and having spaced parallel ears straddling, andhin edly connected with said ear, the walls of said socket being at approximate right angles to said first jaw and characterized by inclined planes of predetermined inclinations, and a metal feed screw overlying said lug in spaced parallelism and adjustably mounted in the screw-threaded hole and having tool accommodating means at one end extending beyond said lug and a ball jointing head at the opposite end, said head fitting into and being swivelly and positively coupled with said socket, said head; having. endv thrust cam coaction with the inclined. wallsv in said socket. said ball and socket connection being in close, proximity to the hinge commotion between said ears.

OSCAR W. S. FREAR.

REFERENCES CITED,

The following references are; of. record in the file of this patent:

UNITED STATES PATENTS 

